Digital cameras and other such imaging devices have surged in popularity in recent years. One type of digital camera is an interchangeable lens type. For example, with this type of digital camera, when an optical viewfinder is used to observe a subject, the light incident on the optical system (that is, a subject image) is reflected by a quick return mirror disposed along the optical path, and is guided to a viewfinder optical system. As a result, the subject image is converted by a pentaprism or the like into an erect image, and guided to an optical viewfinder. Consequently, the user can look through the optical viewfinder to observe the subject image formed by the optical system.
Meanwhile, when an optical system is used for imaging, the quick return mirror is retracted from the imaging optical path. As a result, the viewfinder optical path is switched to the imaging optical path, and when the imaging is finished, the quick return mirror instantly returns to its original position. This method is employed in both conventional silver halide cameras and digital cameras, as long as they are single lens reflex cameras.
However, imaging with an optical viewfinder is extremely inconvenient for a novice who is inexperienced with digital camera photography.
In view of this, an imaging device has been proposed that has a monitor imaging mode (known as live view mode) in which the subject can be observed on a liquid crystal monitor during imaging (see Patent Literature 1, for example).